The 3~(rd) depression of Ordos basin came about under the Yanshan movement after the Trias Jura & Jurassic and the center gradually move to the west, which lead to a huge anisomerous syncline of widely slow eastern side and precipitously narrow west.

• 鄂尔多斯盆地在燕山运动作用下使区内发生了自三叠系和侏罗系后的第三次拗陷,沉降中心不断西移,形成一个东翼宽缓、西翼陡窄的不对称巨型台向斜。